Objective To investigate the causes and treatment methods of complications induced by the long-pulsed alexandrite laser on hair removal. Methods A total of 2 562 patients (3 279 sites) with unwanted hairs were treated by the long-pulsed alexandrite laser. Wave length was 755 nm. With 20 msec pulse width. 12. 5 mm spot size, 12. 0-16. 5 J/cm2 treatment energy, and 50-60 days intermitted between each treatment. Results There were 242 patients with complications such as erythema, eruption, blister, bulla, hyperpigmentation, hypopigmentation, and scar. Conclusion The long-pulsed alexandrite laser on hair removal is effective and safe, and the correct procedures of treatment can reduce the complications.